Products with tape formats having one or more spare areas and apparatuses configured for use with such products

ABSTRACT

An apparatus includes a magnetic head having an array of transducers. The apparatus is configured to read and/or write to a magnetic recording tape according to a format. The format specifies a number of active channels and a contiguous spare area on the magnetic recording tape. The format also specifies compatibility with a second format. The second format specifies a different number of active channels than the number of active channels specified by the format. A product includes a magnetic recording tape and data stored on the product specifying the aforementioned format.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/923,280 filed Jun. 20, 2013, which is incorporated by reference.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to products and apparatuses havingand/or compatible with a tape format having a contiguous spare area.

In magnetic storage systems, data is read from and written onto magneticrecording media utilizing magnetic transducers. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, magnetic tape is moved over the surface of thetape head at high speed. Usually the tape head is designed to minimizethe spacing between the head and the tape. The spacing between themagnetic head and the magnetic tape is crucial and so goals in thesesystems are to have the recording gaps of the transducers, which are thesource of the magnetic recording flux in near contact with the tape toeffect writing sharp transitions, and to have the read elements in nearcontact with the tape to provide effective coupling of the magneticfield from the tape to the read elements.

A continuing goal in tape drive systems is effectively managingplacement of tracks on tape. In particular, track density is nearlydoubling every generation to achieve an approximately 40% per yeargrowth in cartridge capacity within each product family. Another goal isto manage head and electronics designs as channels are added to allowdata rate to keep pace with the growing number of data tracks. Forexample, ongoing goals include using fewer, more integrated ASICs, aleast possible number of head channels, and elimination of multiplexing.

BRIEF SUMMARY

An apparatus according to one embodiment includes a magnetic head havingan array of transducers. The apparatus is configured to read and/orwrite to a magnetic recording tape according to a format. The formatspecifies a number of active channels and a contiguous spare area on themagnetic recording tape. The format also specifies compatibility with asecond format. The second format specifies a different number of activechannels than the number of active channels specified by the format.

A computer program product according to one embodiment includes acomputer readable storage medium having program instructions embodiedtherewith. The program instructions are readable by a tape drive tocause the tape drive to read from and/or write to a magnetic recordingtape according to a format. The format specifies a number of activechannels symmetrically arranged about a center of the array, locationsof data tracks on the magnetic recording tape, and spare areas on themagnetic recording tape. The format also specifies backwardcompatibility with a second format. The second format specifies asmaller number of active channels than the number of active channelsspecified by the format.

A product according to one embodiment includes a magnetic recordingtape, and data stored on the product specifying a format. The formatspecifies a number of active channels and a contiguous spare area on themagnetic recording tape. The format also specifies compatibility with asecond format. The second format specifies a different number of activechannels than the number of active channels specified by the format.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIG. 8 is a partial representational view of a data band of a magneticrecording tape having a contiguous spare area positioned centrally,according to one embodiment.

FIG. 9 is a partial representational view of an array of transducerspositioned according to a format, according to one embodiment, and anarray of transducers positioned according to a second format.

FIG. 10A is a representational diagram of a tape with shingled trackswritten in a serpentine fashion according to one embodiment.

FIG. 10B is a representational diagram of a tape with shingled trackswritten in a non-serpentine fashion according to one embodiment.

FIG. 11 is a partial representational view of a data band of a magneticrecording tape having a contiguous spare area, according to oneembodiment.

FIG. 12 is a partial representational view of a data band of a magneticrecording tape having a contiguous spare area, according to oneembodiment.

FIG. 13 is a partial representational view of a data band of a magneticrecording tape having a non-contiguous spare area, according to oneembodiment.

FIG. 14 is a partial representational view of the data band of FIG. 8having information written in the contiguous spare area, according toone embodiment.

FIG. 15 is a representational view of transducer layouts having varyingnumbers of active channels and both symmetrical and asymmetricalsub-arrays, according to various embodiments.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems, as well as operation and/or component partsthereof. Also described, according to some embodiments, is a contiguousspare area tape format for use with a drive having backwardcompatibility, where the legacy format has a smaller number ofsimultaneously-written data tracks than the newer format.

In one general embodiment, an apparatus includes a magnetic head havingan array of transducers. The apparatus is configured to read and/orwrite to a magnetic recording tape according to a format. The formatspecifies a number of active channels, locations of data tracks on themagnetic recording tape, and a contiguous spare area on the magneticrecording tape. The format also specifies backward compatibility with asecond format. The second format specifies a smaller number of activechannels than the number of active channels specified by the format.

In another general embodiment, an apparatus includes a magnetic headhaving an array of transducers including data and servo transducers. Theapparatus is configured to read and/or write to a magnetic recordingtape according to a format. The format specifies a number of activechannels symmetrically arranged about a center of the array, locationsof data tracks on the magnetic recording tape, and spare areas on themagnetic recording tape. The format also specifies backwardcompatibility with a second format. The second format specifies asmaller number of active channels than the number of active channelsspecified by the format.

In yet another general embodiment, a product includes a magneticrecording tape and a cartridge memory. The cartridge memory has datastored therein specifying a format. The format specifies a number ofactive channels, locations of data tracks on the magnetic recordingtape, and a contiguous spare area on the magnetic recording tape. Theformat also specifies backward compatibility with a second format. Thesecond format specifies a smaller number of active channels than thenumber of active channels specified by the format.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may operate under logicknown in the art, as well as any logic disclosed herein. The controller128 may be coupled to a memory 136 of any known type, which may storeinstructions executable by the controller 128. Moreover, the controller128 may be configured and/or programmable to perform or control some orall of the methodology presented herein. Thus, the controller may beconsidered configured to perform various operations by way of logicprogrammed into a chip; software, firmware, or other instructions beingavailable to a processor; etc. and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (integral or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some approaches, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreapproaches, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or other device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B made of the same orsimilar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 22 data bands, e.g., with 8data bands and 9 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader and/or writers such as 17, 25, 33,etc. An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complimentarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs in apiggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. The writers, exemplified bythe write head 214 and the readers, exemplified by the read head 216,are aligned parallel to an intended direction of travel of a tape mediumthereacross to form an R/W pair, exemplified by the R/W pair 222. Notethat the intended direction of tape travel is sometimes referred toherein as the direction of tape travel, and such terms may be usedinterchangeable. Such direction of tape travel may be inferred from thedesign of the system, e.g., by examining the guides; observing theactual direction of tape travel relative to the reference point; etc.Moreover, in a system operable for bi-direction reading and/or writing,the direction of tape travel in both directions is typically paralleland thus both directions may be considered equivalent to each other.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Generally, the magnetic tape medium moves in either a forward or reversedirection as indicated by arrow 220. The magnetic tape medium and headassembly 200 operate in a transducing relationship in the mannerwell-known in the art. The piggybacked MR head assembly 200 includes twothin-film modules 224 and 226 of generally identical construction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AITiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (−), CZTor Al—Fe—Si (Sendust), a sensor 234 for sensing a data track on amagnetic medium, a second shield 238 typically of a nickel-iron alloy(e.g., ˜80/20 at % NiFe, also known as permalloy), first and secondwriter pole tips 228, 230, and a coil (not shown). The sensor may be ofany known type, including those based on MR, GMR, AMR, tunnelingmagnetoresistance (TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜0.45/55 NiFe. Note that thesematerials are provided by way of example only, and other materials maybe used. Additional layers such as insulation between the shields and/orpole tips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further approaches, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹ (δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle α₃ on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α₃tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used LTO tape head spacing. The open space between themodules 302, 304, 306 can still be set to approximately 0.5 to 0.6 mm,which in some embodiments is ideal for stabilizing tape motion over thesecond module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother approaches, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads.

As alluded to above, various embodiments are associated with a formatfor magnetic tape recording products and systems. Such format addressesthe need for a configuration that enables higher data rate by allowingmore active transducer channels in use per wrap, but at the same timeprovides backward compatibility to at least a previous generation havingfewer active transducer channels in use per wrap.

Consider, for example, Linear Tape Open, 3^(rd) generation (LTO-3),which is a 16 channel format that is backward compatible to LTO-2, whichis an 8 channel format. LTO was created at the outset to accommodateboth 8 and 16 channel formats, and thus enable a transition from 8 to 16channels. Continuing with this example, transitioning from LTO-3 to 32channels and keeping backward compatibility means the pitch betweenchannels needs to be halved again. This creates an asymmetry in theformat, resulting in creation of spare area in a given data band.

“Spare area” may be defined, in some approaches, as area that isnonattainable for user data in the format being used, and is not a guardband positioned adjacent the servo tracks.

In various embodiments, the spare area created by doubling the number ofchannels in, for example, an LTO format is contiguous. In one approach,the spare area that is created is contiguous when, for example, thenumber of channels is doubled in a format wherein the number of activechannels is modulo 4, 8, 16, etc. A contiguous spare area is one whereall the area not written to when a data band is fully written occupiesone area of the tape, e.g., as a stripe along the length of the tape.This does not include guard bands adjacent the servo tracks. Thecontiguous spare area may be centered in the format, may be placedproximate to servo tracks, or at any point therebetween.

Thus, in one embodiment, the format specifies a data structure on themagnetic recording tape, such as a number of active data channels usedto read and/or write to the tape, general locations of data tracks onthe magnetic recording tape, and a spare area on the magnetic recordingtape, where the spare area may be contiguous. The format also specifiesbackward compatibility with a second format (e.g., a legacy format). Inone approach, the second format specifies a smaller number of activechannels than the number of active channels specified by theaforementioned format. The number of active channels specified in thefirst and/or second format may be modulo an even number, where “modulo”means “a multiple of.” The second format in various approaches mayspecify no spare area, a split spare area, or a contiguous spare area.

FIG. 8 depicts a partial view of a preferred embodiment of a product 800in the form of a magnetic recording tape, in accordance with oneembodiment. As an option, the present product 800 may be implemented inconjunction with features from any other embodiment listed herein, suchas those described with reference to the other FIGS. For example, theproduct 800 may be embodied as a cartridge, such as that shown in FIG.1A, and having a cartridge memory with data therein specifying theformat. Of course, however, such product 800 and others presented hereinmay be used in various applications and/or in permutations which may ormay not be specifically described in the illustrative embodiments listedherein. Further, the product 800 presented herein may be used in anydesired environment.

Referring to FIG. 8, there is shown a single data band and servo tracks802 sandwiching the data band. The format preferably specifies modulo aneven number, e.g., 2, 4, 8, 16, 32, 64, etc., of active channels and theexample shown specifies a 32 channel reading and/or writing of datatracks 804, and formation of a contiguous spare area 806 that iscentered relative to the data tracks, and correspondingly, centeredrelative to the array of transducers that read and/or write the datatracks according to the format, in a direction perpendicular to the tapetravel direction. See, e.g., the arrays in FIG. 9.

FIG. 9 depicts a representational view of a preferred embodiment of anapparatus 900 in the form of an array of transducers of a magnetic head,not to scale, configured to read and/or write to a magnetic recordingtape according to a format, in accordance with one embodiment. As anoption, the present apparatus 900 may be implemented in conjunction withfeatures from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, suchapparatus 900 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 900 presented herein may be used in any desired environment.

Referring to FIG. 9, there is shown an array 902 of transducerspositioned according to the format, which in this example specifies 32channel reading and writing. Servo readers S are also shown flanking thearray 902. When the array 902 is viewed in conjunction with the databand of FIG. 8, it is seen that the spare area 806 is centered relativeto the array of transducers. For simplicity, the term “spare area” maybe used herein to also describe area on the magnetic head thatcorresponds to the spare area on the magnetic recording tape. Thus, thearray is logically divided into two symmetrical subarrays oriented aboutthe spare area position and/or center point of the array. This symmetryhas the advantage that the resultant format is symmetrical, which notonly facilitates using the spare area for other functions if desired,but also greatly simplifies fabrication of the apparatus used forrecording data in this format, and deployment of that apparatus in amanner that obviates a need for transducer multiplexing, etc.

As alluded to above, the array 902 may have an inactive region 906corresponding to the spare area, and positioned between the symmetricalsubarrays. For example, the array may not have a middle transducer inthe inactive region 906. Alternatively, a middle transducer may bepresent, but is inactive, e.g., not coupled to a cable, damaged, orsimply not activated during operation of the apparatus. The width of theinactive region, may be approximately 2× the center to center transducerpitch P in one of the subarrays. However, the resulting spare area onthe tape has a width about equal to a sub-data band 810 (e.g., adjacenttracks written by a single transducer or otherwise corresponding to thelateral range of one transducer position in the array). The sub-databand 810 itself, when fully written, may be about equal to the center tocenter transducer pitch P.

In order to provide the backward compatibility with a second format,having a smaller number of active channels than the first array 902, andwhere the smaller number is modulo an even number, various transducersof the array 902 are generally positioned as specified in the secondformat as well. To exemplify, also shown in FIG. 9 is an array 904 oftransducers, not to scale, at positions specified by the second format.In one approach, if the second format specified N channels, the arrayaccording to the format may have 2×N or 2×N+1 transducers.

In one embodiment, the apparatus 900 is configured to read and/or writeto a magnetic recording tape according to the second (e.g., legacy)format, where no contiguous spare area is created when a data band isfully written in the second format. The apparatus is also configured toread and/or write to a magnetic recording tape according to the (e.g.,newer) format, where the contiguous spare area is created when a databand is fully written in the format.

According to various approaches, the apparatus 900 may be configured fornon-serpentine and/or serpentine writing. Additional arrays may bepresent to enable bidirectional writing, read while write capability,etc. The data tracks 804 of FIG. 8 are depicted as being written in aserpentine manner. FIG. 10A depicts shingled data tracks written in aserpentine manner, with tracks 804A written in a first direction andtracks 804B written in the opposite direction in an alternating fashion,from the outside in, as the tape is moved back and forth in sequentialwraps. FIG. 10B depicts shingled data tracks written in a non-serpentinemanner.

FIG. 11 depicts a partial view of another embodiment of a product 1100in the form of a magnetic recording tape, in accordance with oneembodiment. As an option, the present product 1100 may be implemented inconjunction with features from any other embodiment listed herein, suchas those described with reference to the other FIGS. For example, theproduct 1100 may be embodied as a cartridge, such as that shown in FIG.1A, and having a cartridge memory with data therein specifying theformat. Of course, however, such product 1100 and others presentedherein may be used in various applications and/or in permutations whichmay or may not be specifically described in the illustrative embodimentslisted herein. Further, the product 1100 presented herein may be used inany desired environment.

As shown, the data band of the product 1100 includes data tracks 804,servo tracks 802, and a spare area 806 that is offset from a center ofthe data band, and correspondingly from the center relative to the arrayof transducers during writing of the data tracks. In this example, thespare area 806 is proximate a servo pattern 802 on the magneticrecording tape.

FIG. 12 depicts a partial view of another embodiment of a product 1200in the form of a magnetic recording tape, in accordance with oneembodiment. As an option, the present product 1200 may be implemented inconjunction with features from any other embodiment listed herein, suchas those described with reference to the other FIGS. For example, theproduct 1200 may be embodied as a cartridge, such as that shown in FIG.1A, and having a cartridge memory with data therein specifying theformat. Of course, however, such product 1200 and others presentedherein may be used in various applications and/or in permutations whichmay or may not be specifically described in the illustrative embodimentslisted herein. Further, the product 1200 presented herein may be used inany desired environment.

As shown, the data band of the product 1200 includes data tracks 804,servo tracks 802, and a spare area 806 that is offset from a center ofthe data band, and correspondingly from the center relative to the arrayof transducers during writing of the data tracks. In this example, thespare area 806 is between the center and the outer edge of the databand.

Referring to FIGS. 8 and 12, the spare area 806 splits the data bandinto portions located on opposite sides thereof. The groups oftransducers used to write each of the portions, then, can logically beconsidered subarrays of the transducer array, each subarray beingpositioned on an opposite side of the spare area (when in use).

The format may thus specify and/or the corresponding apparatus may beconfigured to, in one mode of operation, write using only one subarrayof the transducers positioned on one side of the spare area. This modemay be used to address tape dimensional instability problems, as thewidth of the data band read and/or written at a given time is less thana width of the entire array.

FIG. 13 depicts a partial view of another embodiment of a product 1300in the form of a magnetic recording tape, in accordance with oneembodiment. As an option, the present product 1300 may be implemented inconjunction with features from any other embodiment listed herein, suchas those described with reference to the other FIGS. For example, theproduct 1300 may be embodied as a cartridge, such as that shown in FIG.1A, and having a cartridge memory with data therein specifying theformat. Of course, however, such product 1300 and others presentedherein may be used in various applications and/or in permutations whichmay or may not be specifically described in the illustrative embodimentslisted herein. Further, the product 1300 presented herein may be used inany desired environment.

As shown, the data band of the product 1300 includes data tracks 804,servo tracks 802, and spare areas 806 that are noncontiguous. The spareareas may be positioned in sub-data bands located between the center andouter sub-data bands. The apparatus for writing such product may includea multiplexer (e.g., in the controller of FIG. 1A) for allowing theapparatus to write and/or read in a legacy format that specifiesnoncontiguous spare areas.

The format may further specify parameters for reading and/or writing inthe spare area, as shown in FIG. 14, which depicts the product 800 ofFIG. 8 with information written in the spare area 806. For example,information may be coded into the spare area, e.g., at the factory. Suchinformation may include date/location of manufacture, productioninformation, including lot, position on jumbo, temperature, humidity,servo writer head deification, tension, etc. In other approaches,information may include auxiliary information such as servo write headdimensions, metadata, etc. The data may be written in an open format,such as is used to store the linear tape file system (LTFS) partitiondata. Further, because in the preferred embodiment the spare area islocated in the center of the data band, the information therein mayprovide a reference location. Thus, for example, the track containingthe data could be very narrow, e.g. 1 um wide (wide enough to read back)and thus serve as reference feature.

Any apparatuses compliant with the format may include at least onetransducer for reading and/or writing in the spare area. For example theapparatus 900 of FIG. 9 may have 33 channels in the above embodiments.

FIG. 15 is a representational view of transducer layouts having varyingnumbers of active channels, and both symmetrical and asymmetricalsub-arrays, according to various embodiments. As an option, any of thepresent layouts may be implemented in conjunction with features from anyother embodiment listed herein, such as those described with referenceto the other FIGS. Of course, however, such layouts and others presentedherein may be used in various applications and/or in permutations whichmay or may not be specifically described in the illustrative embodimentslisted herein. Further, the layouts presented herein may be used in anydesired environment.

Several arrays are shown. Each array includes data transducers 1504 andservo transducers 1506. The transducers are logically divisible into twosub-arrays sandwiching a centerline 1508 of the respective array.

As shown, the arrays include an eight channel array 1502. The eightchannel array 1502 is asymmetrical about the centerline 1508.

A 16 channel array 1510 is backward compatible with the eight channelarray 1502. The 16 channel array 1510 is symmetrical about thecenterline 1508.

A 32 channel array 1512 is backward compatible with the 16 channel array1510 and the eight channel array 1502. The 32 channel array 1512 issymmetrical about the centerline 1508. An inactive area is located nearthe centerline 1508. Thus, this array 1514 is configured to provide aspare area along the centerline 1508.

A 64 channel array 1514 is backward compatible with the 32 channel array1512, the 16 channel array 1510 and the eight channel array 1502. The 64channel array 1512 is symmetrical about the centerline 1508. This array1514 is configured to provide a spare area along the centerline 1508.

An alternate 64 channel array 1516 is backward compatible with the 32channel array 1512, the 16 channel array 1510 and the eight channelarray 1502. This array 1514 is configured to provide a spare area alongthe centerline 1508, as well as spare areas between the servotransducers 1506 and the data transducers 1504 closest thereto. Unlikethe asymmetrical array 1502, the array in this embodiment is symmetricaland thus does not require multiplexing during operation, as would berequired for asymmetrical arrays.

An apparatus according to one embodiment includes a magnetic head havingan array of transducers including data and servo transducers, where theapparatus is configured to read and/or write to a magnetic recordingtape according to a format. The format specifies a number of activechannels symmetrically arranged about a center of the array whichcorrespond to the transducer locations being symmetrical about thecenterline 1508 of the array, locations of data tracks on the magneticrecording tape, and spare areas on the magnetic recording tape. Theformat also specifies backward compatibility with a second format. Thesecond format specifies a smaller number of active channels than thenumber of active channels specified by the format.

It will be clear that the various features of the foregoing systemsand/or methodologies may be combined in any way, creating a plurality ofcombinations from the descriptions presented above.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as “logic,” a “circuit,” “module,” or“system.” Furthermore, aspects of the present invention may take theform of a computer program product embodied in one or more computerreadable medium(s) having computer readable program code embodiedthereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a non-transitory computer readable storage medium. A computerreadable storage medium may be, for example, but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, or device, or any suitable combinationof the foregoing. More specific examples (a non-exhaustive list) of thenon-transitory computer readable storage medium include the following: aportable computer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a portable compact disc read-only memory (e.g.,CD-ROM), a Blu-ray disc read-only memory (BD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a non-transitory computerreadable storage medium may be any tangible medium that is capable ofcontaining, or storing a program or application for use by or inconnection with an instruction execution system, apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a non-transitory computer readable storage medium and that cancommunicate, propagate, or transport a program for use by or inconnection with an instruction execution system, apparatus, or device,such as an electrical connection having one or more wires, an opticalfibre, etc.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fibre cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer, for example through the Internet using an Internet ServiceProvider (ISP).

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart(s) and/orblock diagram block or blocks.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: a magnetic head havingan array of transducers, wherein the apparatus is configured to readand/or write to a magnetic recording tape according to a format, whereinthe format specifies a number of active channels and a contiguous sparearea on the magnetic recording tape; wherein the format also specifiescompatibility with a second format; wherein the second format specifiesa different number of active channels than the number of active channelsspecified by the format.
 2. An apparatus as recited in claim 1, whereinthe spare area is centered relative to the array of transducers.
 3. Anapparatus as recited in claim 2, wherein the array of transducers has aninactive region positioned between symmetrical subarrays of transducers.4. An apparatus as recited in claim 1, wherein the spare area is offsetfrom a center relative to the array of transducers.
 5. An apparatus asrecited in claim 1, wherein the spare area is proximate a servo patternon the magnetic recording tape.
 6. An apparatus as recited in claim 1,wherein the apparatus is further configured, in one mode of operation,to write using only one subarray of the transducers positioned on oneside of the spare area.
 7. An apparatus as recited in claim 1, whereinthe format is modulo an even number, and further comprising at least onetransducer for reading and/or writing in the spare area.
 8. An apparatusas recited in claim 1, wherein a layout of the transducers in the arrayis symmetrical about a center point of the array.
 9. An apparatus asrecited in claim 1, wherein a width of the spare area in a cross trackdirection is about equal to a center-to-center pitch of adjacent ones ofthe transducers.
 10. An apparatus as recited in claim 1, wherein thesecond format specifies a contiguous spare area.
 11. An apparatus asrecited in claim 1, further comprising: a drive mechanism for passing amagnetic recording tape over the magnetic head; and a controllerelectrically coupled to the magnetic head.
 12. A computer programproduct comprising a non-transitory computer readable storage mediumhaving program instructions embodied therewith, the program instructionsreadable by a tape drive to cause the tape drive to: read from and/orwrite to a magnetic recording tape, by the tape drive, according to aformat, wherein the format specifies a number of active channelssymmetrically arranged about a center of the array, locations of datatracks on the magnetic recording tape, and spare areas on the magneticrecording tape; wherein the format also specifies backward compatibilitywith a second format; wherein the second format specifies a smallernumber of active channels than the number of active channels specifiedby the format.
 13. A product, comprising: a magnetic recording tape; anddata stored on the product specifying a format, wherein the formatspecifies a number of active channels and a contiguous spare area on themagnetic recording tape; wherein the format also specifies compatibilitywith a second format; wherein the second format specifies a differentnumber of active channels than the number of active channels specifiedby the format.
 14. A product as recited in claim 13, wherein the sparearea is centered relative to a data band having the spare area.
 15. Aproduct as recited in claim 13, wherein the spare area is offset from acenter of a data band having the spare area.
 16. A product as recited inclaim 13, wherein the format further specifies, in one mode ofoperation, writing using only one sub-array of the channels positionedon one side of the spare area.
 17. A product as recited in claim 13,wherein the number of active channels specified by the format is moduloan even number, and the format further specifies parameters for readingand/or writing in the spare area.
 18. A product as recited in claim 13,wherein a width of the spare area in a cross track direction is aboutequal to a width of a sub-data band.
 19. A product as recited in claim13, wherein information is coded into the spare area.
 20. A product asrecited in claim 13, wherein the second format specifies a contiguousspare area.